IMO 1977 LL USA56

The four circumcircles of the four faces of a tetrahedron have

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IMO 1977 LL USA56

Origin: USA

Problem

The four circumcircles of the four faces of a tetrahedron have equal radii. Prove that the four faces of the tetrahedron are congruent triangles.

Solution

See the solution to (LL67-38).